OK to use a car amp with a passive DIY sub?

Discussion in 'Archived Threads 2001-2004' started by Justin Ward, Jan 31, 2003.

  1. Justin Ward

    Justin Ward Supporting Actor

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    Since I built my ported Tempest sub a while back, I have been using my little JVC mini-system to power it. It probably puts out about 30 watts of true power.
    But it is not the lack of power that bugs me(it goes plenty loud). The extension is terrible. From playing test tones I have determined the minisystem rolls off frequnecy below 35hz. I know the sub hits this low because I used my parents 220 watt Technics amp for a bit and it would shake the hell out of the room at 18hz.
    Now I am looking for a new amp. I want to be as cheap as possible. The salesman at my local Paradigm dealer(same guy who sold me the Titans and CC-170)offered me a car amp he has. It is a Kenwood amp which he claims is rated for about 600(or so)watts, but admits true bridged power is about 150 watts into 4ohms. Assuming I have the hardware to use a 12v component on a 110V AC supply, is it ok to use a car amp?
    Basically what I am worried about is whether or not the amp will play frequnecies from 20hz to about 100hz without any attenuation. Should I be worried or will a car amp do the job?
     
  2. Andrus_R

    Andrus_R Stunt Coordinator

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  3. Cam S

    Cam S Screenwriter

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    I would seriously consider getting an Adire or Parts Express plate amp from one of the canadian suppliers like Creative Sound.

    This will give you everything you need to make the house shake on a limited budget. A pro amp will cost you atleast 600 bucks, as I thought about going that route as well.

    The plates amps have variable phase, LFE in, rumble filters etc etc, you'll be set even with one of the 150 watt versions.
     
  4. Tim Morton

    Tim Morton Stunt Coordinator

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    Get a home amplifier!!!!! Unless you have a HUGE high-end converter and not one of those $150 100watt thingy's. Its always better to run things in the application they were designed for.
     
  5. Seth_L

    Seth_L Screenwriter

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    What they're trying to tell you is, it will cost you more to get a power supply capable of running a car amp than it will cost to get an equally powerful amp that doesn't need it.

    IE: the parts express plate amp.

    Seth
     
  6. Justin Ward

    Justin Ward Supporting Actor

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    If I got the Adire 150 watt amp how could I get rid of the built-in bass boost of 6dB @35hz?
     
  7. Cam S

    Cam S Screenwriter

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    It might be a simple matter of asking for the amp without boost, or doing some simple soldering to get rid of it. I know the AVA250 amp and the PE250 amp can be ordered with no boost. Actually I think my AVA250 amp can't be ordered with any boost anyways.
     
  8. Tim Morton

    Tim Morton Stunt Coordinator

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    I saw an amp selling on PE last night for 100 bucks with a bass boost built in. I think i could deal with the 6db at 30 hz for that price...depending on how the boost is done.
     
  9. Justin Ward

    Justin Ward Supporting Actor

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    Update: I have been looking for amps but I may have a solution. My neighbours have an old Jana stereo amplifier in their garage and they let me take it for free. So, I plan of trying the amp for the job before I shell out the cash for a new amp.

    I am not sure how much power the amp has, but it has two meters on the front that go up to 300 watts on each channel, even it has 1/3 of this much power and it works I'd imagine it be suited for the job. It also has a low cut filter.

    SO if I can get this amp to work, great. But if not I will have to look around some more.
     
  10. Sean Carter

    Sean Carter Stunt Coordinator

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    You could always look for some cheap vintage receiver on ebay.
     
  11. Justin Ward

    Justin Ward Supporting Actor

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    I guess the Jana amp doesn't work. When I hook up the right channel I get no sound and when I hook up the left channel I get a low-rumbling noise from my Tempest and the Tempest cone it moving alot, like an inch. What is wrong. The amp was very cold when I brought it in but it felt warm before I hooked it up(I let it warm for a few hours). Should I let it warm up over night? Any other suggestions to get the amp working?

    If this doesn't work I will probably be off to ebay. Is a vintage reciever just as good as a new one for subwoofer duty?
     
  12. Dave Milne

    Dave Milne Supporting Actor

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    Justin,
    Temperature of the amp shouldn't make a difference --unless there's some flaky intermittent connection. My guess is the amp is toast.

    A vintage receiver should work fine. What are you using for a low pass filter (crossover)?
     
  13. Brett DiMichele

    Brett DiMichele Producer

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    Justin,

    Why don't you tell us what your budget is? Can you spare
    $100.00 ? Can you save up for $100.00 to $200.00 ?

    For $99.00 you can get this amp right now from Parts Express

    http://www.partsexpress.com/pe/pshow...number=300-792

    You are not going to do better than $100.00 for a 120
    watt sub amp that has the needed crossover built in.

    [​IMG]

    "This quality amplifier is perfect for your next subwoofer project. This full featured amp includes both high and low level inputs, both with loop-through capability, phase reversal switch, volume control, defeatable auto on/off (activated by input signal), and a 12 dB electronic low pass filter that is continuously variable from 40 to 160 Hz. The high-level input features a 6 dB high pass filter (125 Hz, 8 ohm) output for satellite speakers. The low-level input also has a -6 dB high-pass filter and gold plated RCA connectors. The amp has thermal, overload and fuse protection for years of reliable use. It is enclosed in a sealed housing and detachable power cord, which make installation a snap! The amplifier sums the right and left stereo inputs to a mono output, so that only one amp is required per system. Specs: * Power: 110 watts RMS into 8 ohms @ 0.1% THD, 156 watts RMS into 4 ohms @ 0.2% THD * Bass boost: 5 dB @ 35 Hz. * Signal to noise ratio: 98 dB (A-weighted) * Dimensions: 8-1/4" W x 10-5/8" H x 4" D * Mounting hole dimensions: 9-5/8" x 7-1/4" * Net wt: 9-1/2 lbs. * Voltage: 115/230 VAC switchable (Note: The standby feature allows the power light to remain lighted when unit is switched to the "off" position.) "
     
  14. Justin Ward

    Justin Ward Supporting Actor

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    I could spare about $150-200 Canadian. I would prefer to go with an external amp so I don't have to make any more mods to my box. But if it is my only choice in this price range I could go for a plate amp. Hwever, if I did go plate, I would probably order the 250 watt PE with no boost as it is only $18 more.
    Any ideas what the approximate duty would be on a PE 250 watt plate amp?
     
  15. Aaron_Smith

    Aaron_Smith Stunt Coordinator

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    Justin, you can always build a separate box for the plate amp- that's what I did. Patman has a good site detailing construction. It also makes it easier if you want to make mods to the amp in the future.
    The 250 watt PE amp is a good buy. You may also want to check out local thrift stores for a used receiver; I have seen plenty here in texas at the $20-$30 level that would do an OK job of driving a sub.
     
  16. Robert_Gaither

    Robert_Gaither Screenwriter

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    I'd advise hit your local pawnshop and get a vintage amp/receiver as these are dime a dozen and dirt cheap if you don't mind too much for the cosmetic reasons (test them on speakers there as well, that's how I picked up my old pro amp Altec Lansing 9444A/SA for a mere $75).
     

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